The present invention relates generally to agricultural machinery and, more particularly, to improvements in balers for harvested crops.
Square balers have a pick-up device, a feeding channel, a baling chamber having side walls, a baling ram, hydraulic adjustment devices to change the position of at least one side wall, and corresponding sensors and monitoring devices which regulate the position of the movable side wall.
A square baler disclosed in European Patent 0 235 397 has a mechanism for controlling the density of the bales by sensing the load on a wall of the baling chamber and increasing the cross-sectional area of the bale chamber when that load exceeds a predetermined value. Sensing is accomplished by measuring the pressure in at least one hydraulic cylinder connected to the baling chamber wall. The disadvantage of the solution described therein is that the device to control the baling pressure cannot be controlled remotely. Furthermore, pressure measuring via a hydraulic cylinder is very costly. In addition, the passive reactions of the hydraulic cylinders operate very slowly and are unsuitable for quickly adjusting the baling pressure.
Sensory devices located at the bailing ram are described in European Patent Application 0 382 263. These sensors supply only an indirect pressure value when the baling ram has arrived at its full stroke position (dead center). During the remaining running time the sensors are unable to collect any pressure information from the baling channel. Depending on the type of harvested crops, these sensors cannot measure the impact the re-expanding crops have on the baling pressure. Therefore these sensing devices deliver incomplete or inaccurate pressure measurements.
An objective of this invention is to provide a system which overcomes these disadvantages.